Electromagnetic fuse



Sept. 2, 1924. 1,506,748

J. w. HAYwooD ELECTROMGNETIC FUSE mwl 2 4o zo IN V EN TOR,

J ATTORNEY )1 Sept. 2 1924.

J, w. HAYWOOD ELECTROMAGNETIC FUSE Filed July 1. 1920 2 Shouts-Sheet PINVENTOR ATTQRAIEY4 @o 7. av 2 1.. 2 2 llllllln 5l 1.

Patented Sept. 2, i924.

UNITED STATES htli PATENT OFFICE.

JOHN V. I'TAYWOOD, 0F NEW YORK, N. Y., ASSGNOR, BY MESNE ASSGNMENTS, ISO

HORNE ELECTRIC 8c MANUFACTURNG COMPANY,

JERSEY.

Application filed July l,

To @ZZ 107mm t may concern.'

Be it known that I, JOHN W. HAYwooD, a citizen of the United States, andresident of the borough and county of Bronx, in the city and State of New York, have invented a new and useful Electromagnetic Fuse, of whichthe following is a specification.

The object of the invention is to provide a serviceable deviceperforming the functions of a fuse and interchangeable therewith in theregular fuse-clips and fuseboxes, but which is not destroyed inoperation and is instantly restorable to normal condition. The devicecomprises an electromagnetic circuit-breaker with magnetic blowout,constituted within the approximate lateral and longitudinal limits of afuse of like capacity, upon a narrow base having terminals adapted tolit between the fuse-clipsln the accompanying drawings forming a parthereof:

F 1 is a side elevation of the device in the open condition;

2 is a vertical longitudinal section showing the closed condition;

Fig. 3 is a sectional plan on the line 3-3 of Fig. 2; f

Fig. l is a. vertical transverse section on the line M4 of Fig. 1;

Fig. 5 is a rear end elevation;

Fig. G is a fragmentary section in the vertical longitudinal plane,illustrating a modification in the closed condition; and

Fig. 7 is a similar view with parts mainly in elevation, showing theopen condition.

The device has a narrow base 1 of insulation, approximating in lengthand width the dimensions of a. fuse body. The base is hollow and open atthe top, and a deep chamber is completed by a hollow cover 2, which ispreferably closed at the rear end and open at the front. Conducting menrbers 3, 3a are embedded in or otherwise se cured to the ends of the baseand are constructed to afford terminals t, 4a adapted to be slipped intoordinary fuse-clips. ln the illust-rated construction the terminals areof the well-known blade form.

An arm 5 is disposed in generally longitudinal relation over the base,this arm being electrically connected with the rear fuseclip terminal e'and cooperating with a stationary contact 6 connected with the frontterminal ll and mounted to swing in the A CORPORATION OF NFFNELECTROMAGNETIC FUSE.

1920. Serial No. 393,387.

vertical longitudinal plane of the base. The body of the arm ispreferably rigid and pivoted toward its rear end upon a transverse pin60, the rear portion 7 of the arm being bifurcated to embrace thestandard et' a bracket 8, by which said pin is carried. A spring 9connected to a tail extension 10 of the arm and anchored to a fixedframe 11 constantly urges the arm to assume the open position of Fig. 1.

The frame 11 is of magnet-ic material and forms part of theelectromagnet 12, by which the arm is caused automatically to open whenthe current in the protected circuit exceeds a predetermined value, suchmovements being produced by the spring 9 upon the displacement of alatch 13, 'by which the breaker arm is normally restrained. Asillustrated, the frame 11 coniprises a vertical bar, embedded orotherwisev secured at the rear end of the magnet chamber lil of the baseand rising therefrom within the enclosure of the cover, together withtwo horizontal longitudinal cores 15, which are united at their rearends to the bar and extend forwardly one above 'the other. The bar 11 ofthe magnet frame is bent forward at the top to provide a longN tudinaltop extension 16, by which the pi\'- oted bracket S is supported, beingsecured thereto by screws 17, 18. A forward support for the cores l5 andthe top extension 15 is constituted by a vertical bar 19 of nonmagneticmaterial, the lower end 2O of which is angled and planted in the basewhile its upper end 21 is reversely angled and united to the topextension by the screw 18. Two holes in the forward support 19, oneabove the other, receive reduced end extensions 22 on the cores. Theenergizing coils 23 are formed and slipped on to the cores prior to theapplication of the piece 19. Said coils are included in the circuitbetween the terminals et, 4t, being preferably connected on the onehandwith the terminal piece 3, as indicated at 2a', and on the otherhand with the pivot bracket 8, by means of a. clip secured by the screw17 and holding the end of the wire of the upper coil.

he pivot bracket 8 is made of conducting non-magnetic material like thatof the arm 5 and the pivot pin 60.

The polar extremities of the cores 15 are in attracting relation to thevlatch 13, which is of magnetic material and constitutes a` the member19.

pivoted armature for the magnet. The latch, thus positioned, cooperateswith a portion of the breaker arm 5 intermedia-te its hinge or mountingand its forward or contact portion. In the illustrated construction itconsists of a bar united at its lower end to a transverse pivot pin 26in the forward part of the chamber 14 of the base and extendingtherefrom substantially vertically through the bifurcated portion 7 ofthe breaker arm and a slot 27 in the top of the cover. At its upperprojecting end it is provided with an insulated resetting handle 28. Thepivot 26 is journaled in the arms of a yoke bracket 29 fixed to the baseby a screw 30 securing it to the foot 2O of An opening 31 is formed inthe upper part of the latch, with its upper edge 32 "beveled toward thefront, to presenta holding edge or catch portion for cooperation with ascrew 33 which passes rearwardly through a screw-threaded opening in anoffset 34 of the arm 5. The rear extremity 35 of said screw is reduced.and unthreaded, so as to form a lateral cylindrical catch surface and arearwardly facing 'alibrating shoulder 36. In the closed condition theside of said reduced portionr bears against the holding edge of thelatch 13, so that the breaker arm is positively held against the pull ofthe spring 9. rl`he shoulder 36 bears against the front face of thelatch, and consequently by turning` the screw in one direction or theother the air gap between the armature and magnet can be varied. Thelatch is urged in the holding direction away from the magnet by a spring37, one end of which is held in a transverse hole in the pivot 26 whilethe opposite end is bent to bear upon the upper end of a screw 38,constituting another calibrating means occupying a screw-threadedopening in the bottom of the base.

The stationary main contact 6 at the forward end of the base isadvantageously formed as a shelf integral with the terminal piece 3 andprojecting at an inclination inward and upward therefrom within thecover 2 and over a forward blow-out chant ber 39 in the base, the saidchamber being separated from the magnet chamber' by a verticaltransverse wall of insulation 40 rising behind the contact 6 to within ashort distance of the normal or closed position of the breaker arm.

The breaker arm 5, from its elevated pivot. inclines forward anddownward in the closed position to bear at its contact portion upon thestationary contact 6, and when the latch is retracted flies up to orslightly beyond the horizontal, as limited by the top of the cover 2.The space below the rear part of the arm is utilized for thelaterally-compact upwardlyprojecting electromagnet 12, A blow-out coil41, consisting of numerous turns of tine wire, is housed within thechamber 39, beneath the contact 6. The core 42 of this coil is disposedtransversely, being supported in openings in the side walls of the base,outside of which said ends are neath the cover of an ordinary fuse-box.

In the preferred construction of the con tact portion of the device, themovable main break contact is formed by the forward part of the arm 5,the under side of which bears tlat upon the upper face of the inclinedstationary contact 6 when the arm is closed. A. goed contact is insuredby providing one of the members-in this instance the armwith a softconducting facing 44 of woven wire or the like, which is brought up overthe sides of the arm and secured at the ltop beneath la block 45fastened to the arm by screws 46, 47. Carbon secondary break contacts48, 4S) are also provided, and in the illustrated construction aredisposed in advance of the main break contacts. rlhe lower contact 48 iscarried by a depressed portion 5t) of thev shelf 6, which forms thelower main break contact, and is insulated from this contact andelectrically connected with one end of the blow-out coil 41. For thispurpose the supporting part 50 is formed with an opening through it, inwhich is held an insulating bushing 51, whereon the contact 48 rests. Anaxial conducting screw 52 secures the contact 48 to the bushing, and isconnected at its lower end to the terminal 53 of the blow-out coil, theother terminal 54 of said coil being electrically connected to theterminal piece PN. The upper carbon contact 49 is fastened by a screw 55to the end of a leaf spring 5G, which projects forward from the breakerarm, to which it is secured by the screw 47. A The relations are suchthat when the breaker arm is closed the spring 56 is flexed away fromthe top of the breaker arm and under tension, so that, when the armstarts to open, the carbon contacts 48, 49 remain in contact for a briefperiod after the main contacts have separated. The blow-out coil, itwill be observed, is in shunt to the primary break and in series withthe secondary break, so that it is short-circuited, or shunted out ofcircuit, when the arm is closed and momentarily carries the full currentwhen the arm starts to open. By energizing the magnetic blow-out foronly a brief period it is possible to use a very small coil composed ofline wire, obtaining an efficient blow-out occupying little space in theelectromagnetic fuse. Such a coil can be conveniently disposed in thepreferred and advantageous manner illustrated,

whereas a coil in circuit all the time would have to be of coarse wireand of relatively large size. Other forms and arrangements involving anormally cle-energized blow-out may be substituted.

The operation will be readily understood. Current may be regarded aspassing from the rear terminal a to the coils 23 of the electromagnet,thence to the mounting 8, to and through the breaker arm, to thestationary contact 6, and thence to the terminal da. Unless the currentincreases to the value at which the device is designed to act, the pullof the magnet is insuiiicient to retract the latch 18 and thebreaker-arm is held closed. If such value is exceeded, however, thelatch is displaced, and the arm flies open under the action of itsspring, the magnetic blowout then acting to suppress the arc which wouldotherwise occur.

Figs. 6 and 7 illustrate an alternate form. The device as a whole may beand preferably is constructed and arranged as in the other views, butthe primary and secondary break contacts are differently disposed. Theforward contact portion of the breaker-arm a does not bear directly uponthe main stationary contact 6a, but upon an interposed movable contactmember 65, which normally rests upon the top of the contact 6a. Theinterposed contact 65 is the equivalent of two contacts in one, aprimary break occurring between it and the Contact 6' and thereafter asecondary break between it and the breaker-arm when the latter isopened. In the particular form illustrated the member comprises a plate,from the bottom of which there projects a stem 66 passing through anopening in the contact 6a. Said stem is insulated from the contact 6a bya bushing 67, wherein the stem is guided, and a spring 68 in the chamberof said bushing constantly urges the member to leave the contact 6a. Astop 69 on the lower part of the stem limits the member 65 to arestricted movement. The magnetic blow-out coil ll is connected at oneend with the stem 66 of the member 65 and at the other end with theterminal member of the fuse, or, which amounts to `the same thing, withthe stationary contact 6a. In this case the current normally passes fromthe breaker-arm 5L through the intermediate member 65 to the stationarycontact 6a, and the blow-out coil is shunted out of circuit as in theother form. When the arm starts to swing away from the base in theopening movement, the member 65 urged by the spring 66 leaves thecontact 6a, thereby opening the circuit at this point, and follows incontact with the breaker-arm for a short distance. During this briefIperiod the current is caused to flow through the blow-out coil, and theblowout magnet is thereby energized. The member 65 soon reaches thelimit of its movement, while the breaker-arm continues to fly upward,and a secondary gap of comparatively wide extent is opened between itand the member 65, the arc which would occur at this region beingsuppressed by the blowout.

lVhile the preferred embodiment has been described in detail, it will beunderstood that numerous changes may be made in respect to form,proportions, arrangements and reversals without departing from theinvention. Terms of orientation are, of course, relative, as the devicemay be installed in any position.

Wlhat I claim as new is:

l. In an electromagnetic fuse, a contact plate, an extension therefrom,an arm adapted to Contact with said extension and forming the maincircuit, a magnetic coil arranged adjacent said plate and having one vofits ends electrically connected therewith, an insulating bushingextending through said extension and a pin extending through saidbushing and in electrical contact with the other end of said coil toform a secondary or blow-out circuit, adjacent to said main circuit.

2. In an electromagnetic fuse, a contact plate, an extension therefrom,an arm adapted to contact with said extension and forining the maincircuit, a magnetic coil arranged adjacent said plate and having one ofits ends electrically connected therewith, an insulating` bushingextending through said extension and a block upon said bushing, a plateunder said bushing, to which said coil is connected, means extendingthrough said bushing for connecting said block and said plate and ablock flexibly supported upon said arm, adapted to contact with saidfirst mentioned block.

3. An electromagnetic fuse, comprising a narrow movable base havingterminals on the ends thereof adapted to lit between fuse-1 clips, agenerally longitudinally breakerarm on said base, an armature latchpivoted on the base and extending upward therefrom to cooperate with anintermediate portion of the breaker-arm, an electromagnet comprising alimb secured to the base and having a forwardly overhanging extension,and a plurality of coil-bearing cores secured to said rear limbextending parallel there-- from 'one above the other into operativerelation with the latch, a pivot mounting for the breaker-arm on saidtop extension, and a forward support for the cores and top extension.

a. An electromagnetic fuse, comprising a narrow movable base havingterminals on tlie ends l'llereo'f adapted to lt between fase-clips, agenerally longitudinal breaker- N arm on said base, electromagneticmeans controlling the release of said arm a sta- 5 tionary Contactconnected with one of the fuse-clip terminals and disposed over theforward part of the base to cooperate with the forward part o thebreaker-arm, and a magnetic blow-out having a core and coil in a chamberbeneath said contact and in rear of said terminal and magnetic sidepieces arranged adjacent the ends of the core of said blow-ont coil andembracing the region of the break of tlie main contact.

JOHN W.- HAYVOOD.

